Upstream blast

ResearchBlogging.org Blast is one of the worst rice diseases. I believe that, thanks to the breeders, most modern varieties have decent levels of resistance. After all, they can be used in varietal mixtures to protect traditional glutinous rice varieties from blast. 1 Unfortunately, much of this resistance is not durable, because the pathogen overcomes it with time.

For a long time, durable resistance has been known to exist in some Japanese varieties. But these varieties have not been useful for resistance breeding, as the resistant parent also brought along undesired characteristics: the offspring always had poor eating quality.

Shuichi Fukuoka and colleagues have found out why. They report in Science 2 that it is because of a tight genetic linkage. Resistance is conferred by the Pi21 locus, and:

The eating quality of plants carrying the elite cultivar’s chromosomal sequence from a point less than 2.4 kb downstream of the Pi21 locus was equivalent to that of the elite cultivar, and the plants showed a high level of blast resistance. In contrast, plants carrying the donor chromosomal sequence up to 37 kb downstream of the Pi21 locus showed inferior eating quality.

By crossing in just the right bit of the chromosome, and making sure that the neighboring areas do not tag along, resistance can now be transferred, without spoiling the taste.

A Japanese banana in northern Italy

An advert in a local gardening magazine for something called Freddi Banana, supposedly a cold-tolerant banana “developed” in the northern Italian region of Alto Adige, led me down some interesting online byways. In one place it is a cross between a Japanese and a Nepalese variety, in another its origin is given as Ryukyu Islands, Japan. That’s the chain stretching from Taiwan to Japan. I found the whole thing hard to believe, but a little research revealed that there is indeed a Musa species in the Ryukyu Islands. This is Musa basjoo, and it is the most cold-hardy of bananas. Various cultivars are available commercially.

Musa basjoo is commonly referred to as the Japanese Fibre Banana and it’s native place is given as the Ryukyu (Liu Kiu) Islands. However, Musa basjoo is not the Japanese Fibre Banana. Musa basjoo is not from the Liu Kiu Islands and not from Japan, it is a Chinese species.

So what is the Japanese Fibre Banana, I hear you ask?

The true identity of the Japanese Fibre Banana became known only in the aftermath of Japan’s defeat in WWII when the Ryukyu Islands came under the control of the United States Civil Administration of the Ryukyu Islands (USCAR). USCAR brought to Okinawa Egbert H. Walker, a staff member of the Department of Botany, Smithsonian Institution who was in charge of the Serviceman’s Collecting Program (SCP) in which US forces members were encouraged to collect and submit botanical and other specimens. But Walker was no desk-bound administrator of the SCP. He was an accomplished field botanist and developed a thorough knowledge of the Ryukyu flora. His work, during which he personally collected over 7,000 plant specimens on Okinawa and neighbouring islands, culminated in his Flora of Okinawa (Walker 1976). Walker made no mention of M. basjoo in this work but did include the ito-basho, Musa liukiuensis, after the treatment of which he commented:

“Seeds from plants [of Musa liukiuensis] in Oku [village in northern Okinawa] were grown in Kingston, Jamaica by the Banana Breeding Scheme of the Banana Board. The seed, seedlings and flowers were reported in 1973 to be identical with those of Musa balbisiana Colla.”

Called ito basho, or “thread banana,” the Japanese Fibre Banana is very important in Ryukyu tradition, much like abacá, a different fibre-producing Musa species, is in the Philippines.

In the old days, bolts of plain-colored, striped and kasuri (ikat) basho-fu were woven in numerous locations across the Ryukyu islands and were used as tribute payments to the Okinawan royalty. In those days, basho-fu was worn by everyone from kings to commoners. Nowadays, however, basho-fu is a luxury cloth that is made only in the village of Kijoka, on the island of Okinawa.