4. DiscussionClimate change is caus

4. Discussion
Climate change is causing negative impacts
on rice production, which is the most important
crop in Vietnam, and its production is mostly
confined to the most vulnerable coastal regions.
Climate change is severely aggravating the
adverse impacts of abiotic stresses on rice
production. Most of the rice production lands in
coastal areas are already being affected by the
rising sea level, increasing the incidences of
salinity. However, salt stress problems in field
crops can effectively be mitigated through the
use of tolerant rice varieties and proper
management and mitigation strategies. It is
imperative to develop salt tolerance rice
cultivars with high yield potential and grain
quality using modern tools of biotechnology.
However, it is often difficult to incorporate salt
tolerance genes into a high yielding varieties by
conventional breeding methods due to the
unexpected linkage drag encountered in the
progenies, which affects yield and grain quality
characteristics of rice cultivars [22, 23].
It is also challenging to achieve a definite
goal of salt tolerance using conventional
breeding strategies when the target gene is
linked with an unfavorable dominant gene [24].
Nevertheless, using the tools of biotechnology,
it is plausible to transfer valuable genes of salt
tolerance stresses in rice without linkage drag
[25]. In this study, Bac Thom 7 was selected as
the recipient parent because it is good quality
rice and always gives high profit for milled rice.
96 L.H. Linh et al. / VNU Journal of Science, Natural Sciences and Technology 28 (2012) 87-99
Figure 5. Graphical representation of the plant IL-30 genotype. Chromosome numbers are located at the top of
the bars. Black portions of the bars are derived from Bac Thom 7 and slash regions indicated the Saltol and
FL478 introgressions. Markers are labeled on the right side of the chromosomes.
Our study focuses on combining the useful
agronomic traits of Bac Thom 7 with saltol
QTL/gen, which attached salt tolerance in
backcross breeding lines by conversion to the
recurrent parent genotype using molecular
genotyping with SSR markers. We successfully
transferred the Saltol from donor line FL478
into Bac Thom 7. The Saltol gene was
identified in an introgression line, highly salt
tolerant FL478 (IR 66946-3R-178-1-1), which
inherited the gene from the Pokkali [26]. L.H. Linh et al. / VNU Journal of Science, Natural Sciences and Technology 28 (2012) 87-99 97
Table 2. Performance of principal agronomic traits and salt tolerance of IL30 and IL32 lines,
which were selected as the most promising lines
Agronomic traits Cultivar/
Breeding line Saltol
present
DTH
(d)
PH
(cm)
PL
(cm) PN PB SB SP SPP TWG
(g)
Bac Thom 7 - 109a
107.5a
21.0a
6.3a
8.3a
3.5a
127 a
137.6a
18.5a
FL478 Saltol 110a
101.2b
22.8b
7.8b
7.6b
3.4a
106b
125.6b
28.7b
IL-30 Saltol 110a
110.3c
21.2a
6.5a
8.1a
3.5a
130a
140.1a
18.7a
IL-32 Saltol 110a
106.5a
21.1a
6.5a
8.2a
3.5a
129.a
a 139.7a
18.8a
LSD (0.05) 0.27 0.38 0.52 0.08 0.10 0.09 0.61 0.56 0.41
Means with the same letter in a column are not significantly different at P

Kết quả (Việt) 1:

4. thảo luậnBiến đổi khí hậu gây ra tiêu cực tác độngvề sản xuất gạo, mà là quan trọng nhấtcây trồng tại Việt Nam, và sản xuất của nó là chủ yếu làhạn chế đặt dễ bị tổn thương vùng ven biển.Biến đổi khí hậu là tình tiết tăng nặng nghiêm cácCác tác động bất lợi của abiotic căng thẳng trên gạosản xuất. Hầu hết sản xuất gạo hạ cánh xuốngkhu vực ven biển đã được bị ảnh hưởng bởi cácmực nước biển tăng, tăng incidences củađộ mặn. Tuy nhiên, muối nhấn mạnh các vấn đề trong lĩnh vựccây trồng có hiệu quả có thể được giảm nhẹ thông qua cácsử dụng các giống lúa khoan dung và thích hợpchiến lược quản lý và giảm nhẹ. Nó làbắt buộc để phát triển lòng khoan dung muối gạogiống với năng suất cao tiềm năng và hạtchất lượng bằng cách sử dụng các công cụ hiện đại của công nghệ sinh học.Tuy nhiên, nó thường là khó khăn để kết hợp muốikhoan dung gen vào một giống cao thu bởiphương pháp chăn nuôi thông thường do cáckéo liên kết bất ngờ gặp phải trong cácprogenies, mà ảnh hưởng đến chất lượng năng suất và hạtđặc điểm của giống cây trồng lúa [22, 23].Nó cũng là khó khăn để đạt được một nhất địnhmục tiêu của muối khoan dung việc sử dụng thông thườngchăn nuôi chiến lược khi gen mục tiêu làliên kết với một bất lợi chi phối gen [24].Tuy nhiên, bằng cách sử dụng các công cụ công nghệ sinh học,nó là chính đáng để chuyển gen có giá trị của muốikhả năng chịu áp lực trong gạo mà không có liên kết kéo[25]. trong nghiên cứu này, Bắc Thom 7 đã được chọn làmngười nhận cha mẹ bởi vì nó là chất lượng tốtrice and always gives high profit for milled rice. 96 L.H. Linh et al. / VNU Journal of Science, Natural Sciences and Technology 28 (2012) 87-99Figure 5. Graphical representation of the plant IL-30 genotype. Chromosome numbers are located at the top ofthe bars. Black portions of the bars are derived from Bac Thom 7 and slash regions indicated the Saltol andFL478 introgressions. Markers are labeled on the right side of the chromosomes.Our study focuses on combining the usefulagronomic traits of Bac Thom 7 with saltolQTL/gen, which attached salt tolerance inbackcross breeding lines by conversion to therecurrent parent genotype using moleculargenotyping with SSR markers. We successfullytransferred the Saltol from donor line FL478into Bac Thom 7. The Saltol gene wasidentified in an introgression line, highly salttolerant FL478 (IR 66946-3R-178-1-1), whichinherited the gene from the Pokkali [26]. L.H. Linh et al. / VNU Journal of Science, Natural Sciences and Technology 28 (2012) 87-99 97Table 2. Performance of principal agronomic traits and salt tolerance of IL30 and IL32 lines,which were selected as the most promising linesAgronomic traits Cultivar/Breeding line SaltolpresentDTH(d)PH(cm)PL(cm) PN PB SB SP SPP TWG(g)Bac Thom 7 - 109a 107.5a 21.0a 6.3a 8.3a 3.5a 127 a 137.6a 18.5aFL478 Saltol 110a 101.2b 22.8b 7.8b 7.6b 3.4a 106b 125.6b 28.7bIL-30 Saltol 110a 110.3c 21.2a 6.5a 8.1a 3.5a 130a 140.1a 18.7aIL-32 Saltol 110a 106.5a 21.1a 6.5a 8.2a 3.5a 129.aa 139.7a 18.8aLSD (0.05) 0.27 0.38 0.52 0.08 0.10 0.09 0.61 0.56 0.41Means with the same letter in a column are not significantly different at P<0.05. Abbreviations present agronomical traitswhich presented in the Materials and MethodsHere, we used the MABC breeding methodto transfer the saltol gene into a popular cultivarby phenotype and genotype selection. UsingSSR markers (RM493, RM3412b) for the saltolgene ensured efficient foreground selection.The co-dominant nature of SSR markers couldbe very useful in addition to gene-basedmarkers for the introgression of the saltol locusinto a wide range of recipient elite cultivars.The selfed progenies or recombinanthomozygote plants in the target region wereselected from 300 to 478 plants for eachbackcrossing genenration with foregroundselection. Our results demonstrate that a majorsalt tolerance gene (saltol) from the donorparent FL478 was successfully transferred intothe Bac Thom 7 genetic background andexpressed a similar phenotypic characteristicswhen compared with Bac Thom 7.5. ConclusionsWe have developed a salt tolerance of BacThom 7 variety by using marker-assistedbackcross, which was control by a major SaltolQTL. The recovery of the recurrent parentgenome by molecular genotyping and selectioncould increase the efficiency of the MABCstrategy, and this was achievable in a short spanof time. This study could have an good impactin rice breeding and it is applicable for theintroduction of important agronomic traits intothe genomes of popular rice cultivars.AcknowledgementsThis work has been supported by DANIDA(Project code: 09-P01-VIE). We would like tothank the staff and students in VietnamAgricultural Genetics Institute for field work.Thanks also send to the staff of theInternational Rice Research Institute (IRRI) fortheir technical aids.Refere