Characterization of Nepalese Barley Gene Pool for Leaf Rust Resistance

Barley (Hordeum vulagare L) is the major crop for the people living in the high hills and mountainous region of Nepal. Leaf rust (caused by Puccinia hordei) is one of the major production threats for barley cultivation. A lot of variation can be observed on Nepalese barley accessions with respect to leaf rust resistance characteristics. Two hundred and forty one barley accessions were screened for leaf rust resistance characteristics on heading stage at Khumaltar, Lalitpur, Nepal. Among them, one hundred and nine Nepalese barley accessions showing promising for disease resistance were screened using six SSR markers linked to leaf rust resistance genes. Bonus and Local Jau was used as the resistant and susceptible check respectively. Leaf rust resistance genes Rph1, Rph2, Rph3, Rph7, QBLR-P and QTL on chromosome 5HS were detected on Nepalese barley accessions using respective SSR markers. Eight Nepalese barley accessions showed presence of three and more leaf rust resistant genes. The poor relationship between the field disease resistance and molecular markers linked with specific leaf rust resistance gene proved that Nepalese barley gene pool contains other leaf resistance genes

Selection of Pyramided Barley Advanced Lines for Stripe Rust, Leaf Rust and Crown Rust Diseases Using Molecular Markers

Barley diseases are the major yield limiting factors for barley cultivation in Nepal. Stripe/Yellow rust (P. striformis f.sp. hordei and P. striformis f.sp. tritici), leaf rust (Puccinia hordei), and crown rust (P. coronata) are the major rust diseases in Nepal. Pyramiding resistance genes against all these rust diseases are possible through molecular marker assisted breeding. Sweden originated barley variety ‘Bonus’ is found resistant to stripe rust and having linked microsatellite markers for stripe rust and crown rust resistance. Similarly, Nepalese hull-less barley variety ‘Solu Uwa’ and Nepalese awn-less barley landrace NPGR Acc# 2478 have linked microsatellite markers for leaf rust resistance. Therefore, one polymorphic sequence tagged sites (STS) marker (ABG054) for stripe rust resistance, two polymorphic simple sequence repeats (SSR) markers (Bmac0144h and HVM049) for leaf rust and one polymorphic SSR marker (Bmag0006) for crown rust resistance were used to select the advanced barley lines (at F8 stage) from above parents. Field screening of stripe rust resistance was also conducted. Among 51 advanced and field disease resistance lines from Bonus/Solu Uwa cross, we have selected 10 pyramided lines for all three types of barley rust resistance. Similarly, among 39 advanced and field disease resistance lines from Bonus/NPGR Acc#2478 cross we have selected three pyramided lines and advanced for further yield testing for general cultivation purpose. The chances of losing the desired gene are high in late generation selection using molecular marker assisted selection (MAS); but the chances of getting agronomically superior varietal output will also increase

Marker Assisted Screening of Nepalese rice for bacterial leaf blight (BLB) resistance

Bacterial Leaf Blight (BLB) is the most important yield limiting factor in Nepalese rice. BLB resistance rice varieties are highly demanding in the country. Breeding efforts for developing disease resistant depends on availability and use of resistant gene donors. Nepalese rice landraces could be the source of resistant gene. Therefore, ninety six Nepalese rice accessions were screened using eight Simple Sequence Repeats (SSR) markers and one Sequence Tagged Sites (STS) marker for presence and absence of BLB resistance gene. We have detected BLB resistance gene Xa-10 on five accessions, Xa-13 on six accessions, Xa-7 on 23 accessions, Xa-3 and Xa-4 on 52 accessions, Xa-5 on 25 accessions, Xa-8 on 30 rice accessions. No any rice accessions tested have Xa-21. Similarly, 17 rice accessions showed three and more than three BLB resistance genes. Presence of Xa-13 on susceptible check variety CNTRL-85033 confirmed that this resistant gene is not working in Nepalese rice field. Therefore, Nepal need to pyramide the BLB resistant genes for durable resistance.Nepal Journal of Biotechnology. Dec. 2015 Vol. 3, No. 1: 35-3