Bacterial blight (BB) is a serious disease of rice in India. We have used molecular marker-assisted selection in a backcross breeding program to introgress three genes (Xa21, xa13, and xa5) for BB resistance into Triguna, a mid-early duration, high yielding rice variety that is susceptible to BB. At each generation in the backcross program, molecular markers were used to select plants possessing these resistance genes and to select plants that have maximum contribution from the Triguna genome. A selected BC3F1 plant was selfed to generate homozygous BC(3)F(2) plants with different combinations of BB resistance genes. Plants containing the two-gene combination, Xa21 and xa13, were found to exhibit excellent resistance against BB. Single plant selections for superior agronomic characteristics were performed on the progeny of these plants, from BC(3)F(3) generation onwards. The selected plants were subjected to yield trials at the BC(3)F(8) generation and were found to have a significant yield advantage over Triguna. The newly developed lines are being entered into national multi-location field trials. This work represents a successful example of the application of molecular marker-assisted selection for BB resistance breeding in rice.

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Bacterial blight (BB) of rice caused by Xanthomonas oryzae pv. oryzae is one of the most destructive diseases of rice in majority of the rice growing countries especially in Asia. As the chemical control of this disease is not very successful, greater emphasis has been given on host plant resistance. In the present investigation, rate of multiplication of Xoo was observed in three different rice varieties having different levels of resistance against BB viz., TN1 (susceptible), Ajaya (moderately resistant) and Improved Samba Mahsuri (ISM) (resistant). The results revealed that rate of multiplication was faster in susceptible TN1 after 5th day, population shot up at POI in TN1 and gradually decreased after 7th day probably due to the rapid death of leaf tissue and unavailability of nutrients, and however the movement of the bacteria was also high in TN1 when compared to other two varieties Ajaya, Improved samba mahsuri. However, there were significant differences in Xoo population at 1 cm below POI. At 1 cm below of POI, Xoo multiplied rapidly in TN1 compared to resistant variety, ISM.

Rice false smut disease is gaining importance because of its impact on the grain yield and its toxin production ability. Fifty-eight isolates of Ustilaginoidea virens were collected from different rice-growing regions of India. DNA of U. virens was isolated by the CTAB method and fifty ISSR primers were screened for molecular variability studies. Twelve primers viz., UBC series 807, 808, 809, 810, 811, 812, 834, 835, 836, 840, 841, and 842 were selected to study the genetic variability. Different parameters of tested primers viz., heterozygosity (Hn), polymorphism information content (PIC), effective multiplex ratio (EMR), marker Index (MI), and resolving power (RP) were calculated. Primers UBC 812 and UBC 809 recorded maximum heterozygosity (Hn). The PIC values ranged from 0.10 to 0.27 and UBC 807 recorded the maximum value of 0.27. The EMR value varied from 6.75 to 24.0, Similarly, UBC 807 recorded the highest value of MI (24) and RP (8.55). A dendrogram was generated using the DARwin software (version 6.0.21A) based on the unweighted neighbor-joining cluster method. All the fifty-eight U. virens isolates were grouped into three major clusters. Clusters I and II had 21 and 35 U. virens isolates respectively. Cluster III had only two isolates. The isolates showed genetic variations and there was no specific grouping based on the geographical distance.

DRR Dhan 54 [IET 25653 (RP 5943-421-16-1-1-B)] was released for aerobic system of cultivation in water limiting areas of Zone II (Haryana), III (Odisha, Bihar and Jharkhand), VI (Gujarat) and VII (Telangana) through Central Sub-committee on Crop Standards, Notification and Release of Varieties for Agricultural Crops vide S.O. 500(E) dated 29th Jan 2021 [CG-DL-E-03022021-224901]. DRR Dhan 54 was developed from the cross of RP 5124-11-4-3-2-1/IR 78877-208-B-1-1. It was tested in Aerobic trials in AICRIP during 2015-2018 and found to be a top ranking entry on overall basis in three years (2018, 2016 and 2015). Across multiple zones, DRR Dhan 54 ranked 1st with 15.8%, 4th with 12% and 5th with 17% yield advantage over the BVC in 2018, 2016 and 2015, respectively indicating its wider adaptability and yield stability. It has desirable grain quality traits in terms of high HRR%, intermediate AC% and multiple pest and disease resistance.