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Breeders Fusarium update

Peter Reid and Warwick Stiller, CSIRO plant Breeders, outline Fusarium status on the Darling Downs and breeding objectives

Peter, you’ve just visited the Darling Downs, do you think the incidence of fusarium is as bad this season with the prolonged wet season that they’ve had there?

I got the impression it was fairly variable. We certainly saw some quite serious fusarium in some fields but over all I was probably a little surprised that it wasn’t worse given all the waterlogging and cool, wet weather etc but I guess it illustrates we don’t really fully understand all the factors which bring the fusarium along.

Nether the less, you’ve got a fairly large fusarium program in the Darling Downs looking at those nurseries. Actually what is the size of the program this year relative to what it’s been in the past?

It’s slightly bigger I guess again than it has been in recent years. We’re up to almost nine thousand plots over two nurseries at Pampas and Norwin and that’s an awful lot of work and we are overly assisted by CSD staff and also Qld DPI staff in running these trials.

The components of the trials, what are they actually made up with?

Well right through the breeding program I guess from even single plant selections, progeny rows through more advanced material and that of course covers both conventional varieties and transgenic right from particularly Bollgard® IIs that we are concentrating on a lot now and Bollgard® II Roundup’s and also straight Roundup Readys.

In the past we still are using Sicot 189 as the standard and we’ve got some other varieties like Sicot 70 and Siokra V-18 that are quite good for fusarium and for yield, but what are you going to do in the future with regard to standards for Bollgard® II?

Well I guess our basic standards are still Sicot 189, that’s the comparison we use for deriving F.ranks for new varieties so while it’s still the standard we’ll continue to use it but I think as time goes on we’ll evolve probably other standards as well so in future we’ll probably will have a Bollgard® II standard but I guess that has to be discussed with some of the other researches etc to decide on what the new standards might be. As time goes on I think we’ll get a standard with a higher F.rank than Sicot 189 as we get more and more material with better resistance.

With the fusarium tolerance of the Bollgards, are they as good as their recurrent parents?

Yes, at least as good. We certainly aim where possible to lift the resistance and we certainly appear to have succeeded in doing that. We would expect that I think in all cases from our last years data, the Bollgard® IIs are probably a little higher than their recurrent parents so we’ve been pretty pleased with the progress we’ve made with them.

With the initial Bollgard® II lines that are out there this season, the Sicot 14B has been quite good, it’s so far had an F Rank of close to 141. Any ideas of what the F.ranks will actually be of the new Bollgard II varieties that have been released next season?

Certainly there will be a range and I said they are looking quite promising. We’ll certainly have things well over the 100 in most of the new Bollgards and certainly some in the 120 range and around that area I think, but the final data will be released obviously as we get this years data and put it all together but we’d certainly expect F.ranks of I’d say at least around the 120 area.

Warwick, just discussing a little bit about where resistance comes from, do cotton breeding lines from other countries have resistance to the fusarium strain that’s in Australia?

Rob, I guess that generally we found that at least the commercially cultivated cotton lines that we’ve sourced from around the world from sort of the major cotton producing countries really generally don’t have mush resistance towards our fusarium. Again there is a bit of a range but generally at least nothing better than what we see amongst our own material that we have here.

Where do you start to get fusarium resistance from then?

Initially the first place we look for fusarium resistance is from within our own program and Sicala 45 is a good example of that. We’ve been able to recombine and reselect from within our won material to get some things with quite good resistance, as I said like Sicala 45. Once we’ve sort of mined that sort of germplasm I guess and there is some work still to be done there but once that’s run out the gains are going to be made from some other exotic material that we can identify. We do have some of that in the program now. Some of it’s looking encouraging.

After that it sort of becomes difficult. We have identified some other species, some other things related to cotton that may have some additional resistance and as well as some of the native cottons that have been talked about in the past, the Gossypium Sturtianum again shows some promise. All those things are going to be very long-term sort of projects and that the challenge with all those things is to be able to not only have something with resistance but also have something that produces an economic yield as well.

We’ve come a long way with fusarium tolerance over the last five years and now a lot of the new varieties that are released now are improvements or better than the standard. Some of them as I mentioned before with an F Rank of some of the Bollgards like 141 this past season. How far can you go with that resistance?

That’s a very good question Rob. As I mentioned all these things are very long-term and we are working very hard to try and continually improve that. I guess as it stands now we haven’t found anything or any combination of genes that do produce good enough resistance for those bad fusarium fields and that’s going to be a continual challenge.

I guess there’s no real good answer to that question apart from the fact that we are going to get progressively better resistance and hopefully at some point in time in the not too distant future we will be able to identify something that at least has resistance good enough for most of those fusarium areas. To be able to get something that can be grown in those bad fusarium fields, in a bad fusarium year is going to be a big challenge and I don’t think we’re quite there yet.

Peter the F.rank system is now commonly used, and I guess the system’s being used to report the resistance of new varieties as they come along. What sort of confidence do you have in that F.rank system now that it’s been used for that length of time?

I think it’s a good system, it’s at least given the farmers a good benchmark on how they can compare varieties over time and particularly new ones coming along but it’s by no means certainly not perfect and farmers need to recognise it’s limitations, particularly with things which don’t have too many trials when something new is presented with a relatively small number of trial results that people certainly need to be cautions about that rank.

Further Information:  Robert Eveleigh, John Marshall, or Craig McDonald