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Accueil du site → Doctorat → Inde → 2003 → Diversity analysis and identification of sources resistant to downy mildew, shoot fly and stem borer in wild sorghums

Osmania University Hyderabad (2003)

Diversity analysis and identification of sources resistant to downy mildew, shoot fly and stem borer in wild sorghums

Venkateswaran, K

Titre : Diversity analysis and identification of sources resistant to downy mildew, shoot fly and stem borer in wild sorghums

Auteur : Venkateswaran, K

Etablissement de soutenance : Osmania University.

Grade : PhD thesis 2003

Sommaire partiel
Sorghum [Sorghum hirolor. (L.) Mocnch], is an important cereal crop sustaining tllc livelihood of thc rcsourcc poor farmers in the semi-arid tropics, hil, ?lor advanccnlcnts in crop improvement liavc rcsultcd in short-statured, photo-insensitive and high-yiclding varieties suitable for divcrsc agro-cliniatic conditions. Even so, productivity of cultivated sor- ghum continues to bc constrained by various biotic and abiotic strcsscs ( oggctt, IOSS). Wild relatives and progellitor species ofSo) liiojr r-cprcscnt a potential gcnctic rcsourcc that has not been fully cxplorcd 14s-a-vis sorghum breeding. Rcl rcscnlcd by 24 spccics. distributcd in five taxc)nonlic sections (.iorg/iio)i, c,/ iicto.ror.ghiii)i, iretcr.o. or i ioli.  UI YOI ; I I I ?I anti s1i )o. oi ;q111 111), mcmbcrs oftllc genus iirc spread across Asia. Africa and Australia (Doggclt 1988 ; Lazol.itlcs I091 ). ’T’licsc uild sorgliunis could hc used to cfl’cctivcly broaden tllc gcnctic basc and proviric alternate sources of rcsist:incc genes for thc long tern1 control of major biotic !abiotic stresses. Witli this in vic\v, tllc prcsalt investigation \\.as undcl-taken to study thc diversity among \vild sorghunls at tlic mo pliological and molcculas levels and also to identify sourccs ofrcsist- ancc to sorglium dolvny mildcw, sorgllum slioot fly and spottcd stem borer. Eighty-livc accessions of wild sorghums, wliicll are distributcd in livc taso io nic scclio ls, could be clcarly identified based on diag lostic morphological traits. llistinct gcnetic differ- c lccs wcrc obscrvcd for tl c quaiititativc traits in both rainy and post-rainy seasons. Leaf widrh, pcdunclc cxcrtion, pn iiclc lcngll and nun bcr of ,acllis nodes sho\vcd the Iliglicst broad sense hcritabilitp suggesting Lliat tlicy arc less nffectcd by tllc scason and tllcrcfore, can he clTcctivcly used as sclcctiori criteria in brccdingprogramn es. Further, thc high phcnotyp c \ti si ;tbility obt ; innl Ihr tlic il ; lllitali\,c tri its li cilit ;ilctl a clc ; r tlistinction oflaxa indicating tlic csistcrlccol’gro p spccilic ; dal)tatloi s. Molecular diversity in 22 acccssiorls belonging lo the five sections ant1 rcpresenting 17 spccics was asscsscd using (I) four niaizc mitochondriaI( t) DNA probes, (ii) four sorghum tlcrivctl rcsisti ncc gcnc candidates, (iii) four AFLI’ primcr combinations and (iv) I0 SSR j ri ner sets. Tllc same AFLI’ and SSRprirncr sets \yere also used to study the intra-specific tlivcrsity ivitllin 21 ;ICCCSS OI S rc >rcscnting tlic four \jild races of S.l)ic,olor subsp.  o ticii/ /lor r,)i of sccti n sol /i lt

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