CIMMYT Releases Five New Maize Lines With Drought, Heat and Pest Resistance Built In
10 November 2026, New Delhi: The International Maize and Wheat Improvement Center (CIMMYT) has released five new maize inbred lines carrying combinations of drought tolerance, heat tolerance and resistance to fall armyworm and two major fungal diseases, giving breeders in Asia and beyond new raw material for hybrids suited to increasingly erratic growing conditions.
The lines, coded CML661A through CML665B, were announced on October 22 by CIMMYT’s Global Maize Program through its Asia breeding hub, which works across a region stretching from Central Asia to southern China. Dr Ashish Saxena, director of the Global Maize Program, is named as the contact for further detail on the release. An inbred line is a maize plant that has been self-pollinated over many generations until its genetic makeup is fixed and uniform. Breeders use such lines as parents to produce hybrid seed, the commercial product that most farmers plant, by crossing two different inbred lines to combine their strengths.
Unlike a single-gene breakthrough, this release is a conventional breeding product: the outcome of repeated crossing, selection and testing under stress conditions rather than direct genetic modification or gene editing. CIMMYT’s team evaluated the lines in hybrid combinations under drought, heat and pest pressure as well as under normal growing conditions, then tested their behavior as both female and male parents to see how well they combine with other breeding material. Each line was also sorted into one of two broad genetic groups, labeled A or B, which breeders use to decide which lines are likely to produce strong hybrids when crossed with each other. All five lines are rated for an intermediate maturity window and for rainfed tropical growing conditions, meaning they are bred for areas that depend on rainfall rather than irrigation.
Traits across the five lines and what they target
CML661A is an orange flint-kernel line bred for tolerance to fall armyworm, an invasive caterpillar pest that has spread across Asia and Africa in the past decade and can destroy young maize plants, along with drought tolerance and long cobs; CIMMYT recommends it mainly as a female parent because of its strong seed yield. CML662B, an orange-kernel line, is suited to drought-tolerant hybrids and is flexible enough to use as either parent. CML663B, a yellow-kernel line, combines heat tolerance with moderate resistance to Fusarium ear rot and Fusarium stalk rot, two fungal diseases that can cause grain to rot in the field or weaken stalks before harvest; it has already been used as a parent in two hybrids, CAH204 and CAH219, which have been released commercially in India, Nepal, Pakistan and China. CML664A pairs high yield potential and heat tolerance with resistance to turcicum leaf blight, a fungal disease that damages leaf tissue and can cut yields significantly in humid conditions, as well as Fusarium stalk rot. CML665B rounds out the set with high yield potential, heat and drought tolerance together, and resistance to both Fusarium ear rot and turcicum leaf blight; it is the parent of a separate licensed hybrid, CAH205.
CIMMYT cautions that release does not guarantee a line will perform well as a parent in every environment. Instead, the lines are offered to national breeding programs and seed companies as promising starting material, to be tested further in their own hybrid combinations and local conditions before any new commercial variety reaches farmers.
Why breeding programs value this kind of release
Maize is a staple food and feed crop across large parts of Asia, and the region’s smallholder farmers are especially exposed when a single season of drought, an unusually hot spell, or a fall armyworm outbreak arrives without warning. Commercial hybrids that stack several of these defenses at once can reduce the chance that one bad season wipes out a harvest, without requiring farmers to change how they grow the crop. Because fall armyworm has no fully reliable chemical control once an outbreak is underway, breeding tolerance directly into maize is one of the few tools available that does not depend on repeated insecticide use.
CIMMYT makes its inbred lines freely available to public and private sector breeders worldwide under a standard material transfer agreement, a legal arrangement that allows researchers to use the genetic material for further breeding while limiting other uses. Seed is distributed only in limited quantities through CIMMYT’s germplasm bank on request, since the lines are meant as breeding parents rather than as seed for direct planting by farmers. National agricultural research programs and seed companies are expected to cross these lines into their own breeding pipelines, a process that typically takes several more years before a resulting hybrid reaches commercial sale.
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