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Update: CIMMYT maize inbred lines and pre-commercial hybrids with potential resistance to maize lethal necrosis (MLN)

May 22, 2014

By B.M. Prasanna/CIMMYT

Since 2011 MLN has become a disease of serious concern in Kenya, Tanzania, Uganda and possibly Rwanda. CIMMYT has been working in close collaboration with the Kenya Agricultural Research Institute (KARI), private sector partners and virology experts from the USA to combat the disease through host-controlled resistance.

MLN-susceptible line (CML505) versus MLN-resistant inbred line (CLRCY034).

A CIMMYT-KARI MLN screening facility was established at Naivasha in September 2013, and a large array of maize germplasm is presently being evaluated against the disease under artificial inoculation. Subsequent to the development of effective protocols, CIMMYT and KARI have been conducting MLN screening trials in Kenya since 2012, to identify promising inbred lines and pre-commercial maize hybrids with resistance to MLN.

A promising pre-release CIMMYT hybrid versus an MLN-susceptible commercial check.

This is the second update of the information on potential MLN-resistant or moderately resistant inbred lines and pre-commercial hybrids (crossed with CIMMYT varieties), following the first update that was shared with public and private sector partners in May 2013. An evaluation of CIMMYT inbred lines and pre-commercial hybrids was done under artificial inoculation during 2013-2014 in two independent trials, at Narok and Naivasha sites in the Rift Valley, Kenya (Tables 1 and 2).

In each trial, the entries were grown in at least two replications, and MLN severity scores were recorded at different stages of crop growth (vegetative and reproductive stages) on a 1-5 scale (1 = no disease symptoms, 5 = extensive damage). The highest MLN severity score recorded across different trials on a particular entry, and the corresponding disease response rating, are presented here. For a list of the new lines and hybrids, click here.