Efficient Agrobacterium-mediated Transformation of The Elite–Indica Rice Variety Komboka

Abstract

Genetic transformation is crucial for both investigating gene functions and for engineering of crops to introduce new traits. Rice (Oryza sativa L.) is an important model in plant research, since it is the staple food for more than half of the world's population. As a result, numerous transformation methods have been developed for both indica and japonica rice. Since breeders continuously develop new rice varieties, transformation protocols have to be adapted for each new variety. Here we provide an optimized transformation protocol with detailed tips and tricks for a new African variety Komboka using immature embryos. In Komboka, we obtained an apparent transformation rate of up to 48% for GUS/GFP reporter gene constructs using this optimized protocol. This protocol is also applicable for use with other elite indica rice varieties.

Rice Yellow Mottle Virusresistance by genome editing of theOryza sativaL. ssp. japonica nucleoporin geneOsCPR5.1but notOsCPR5.2

“…The next step will be to transfer this approach to an elite variety better adapted to rice culture in rainfed lowland and irrigated areas of Africa, where rice production is particularly affected by RYMV disease. Suitable transformation protocols have been established (Luu et al ., 2020). To obtain more robust resistance, it will be important to stack the three known resistance genes to be able to also protect against new RYMV variants that could break the resistance genes if deployed individually.…”

OsSWEET11b, a potential sixth leaf blight susceptibility gene involved in sugar transport‐dependent male fertility

“…Seeds were placed onto half‐strength Murashige & Skoog (½MS) medium supplemented with 1% sucrose and 0.4% agarose in darkness at 30°C for 3 d. Emerging seedlings were grown in constant light (200 µmol m −2 s −1 ) for 1 wk in a growth chamber. Next, 10‐d‐old seedlings were transplanted into 2 l round pots (16.7 cm diameter, 13.2 cm high) filled with soil (Luu et al ., 2020). Plants were grown in glasshouses at Düsseldorf University (Germany) until maturity; light was supplemented with BL120 LED lamps (Valoya, Finland) to >400 µmol m −2 s −1 , at 30°C : 25°C, day : night, relative humidity 50–70%.…”

Genome editing of an African elite rice variety confers resistance against endemic and emergingXanthomonas oryzaepv.oryzaestrains

“…Rice seed germination and plant cultivation at HHU were done as described (Luu et al, 2020). Briefly, rice seeds were sterilized and germinated onto ½ Murashige Skoog media, supplemented with 1% sucrose.…”

“…This exemption provides a regulatory framework for the introduction of genome-edited, BB-resistant rice into Africa. To provide small-scale rice producers with BB-resistant rice cultivars, we used an efficient transformation protocol (Luu et al, 2020) to introduce BB resistance into a rice cultivar popular in East African countries. Komboka (IRO5N-221) is a high-yielding, semi-aromatic rice variety jointly developed by IRRI (International Rice Research Institute and KALRO (Kenya Agricultural & Livestock Research Organization; BBSRC Varieties Kenya.pdf ) that grows to an average height of 110 cm and has a yield potential of ~7 tons/ha, almost twice that of Basmati, a popular variety planted in Kenya and Rwanda ( The Star 2020 ).…”